DE19505800C2 - Device for controlling a clutch - Google Patents

Description

The invention relates to a clutch for the transmission of torque elements between two parts rotatable relative to one another, the comprises a friction clutch, the friction elements each with the one and the other of the mutually rotatable parts rotate are firmly connected, the friction clutch over at least a displaceable piston can be acted upon, the one with viscous liquid filled, connected to a reservoir Pressure space limited on one side, the rotation housing of which one of the rotatable parts and the rotating piston ge is formed and in one with the other of the rotatable parts connected rotating body rotates. With viscous liquid is meant one with high viscosity, such as common in viscous couplings.

A coupling of this type is from US 4 905 808 known. Here rotates at a differential speed between the rotating parts in a viscous liquid filled chamber an axially star-shaped disc. Between the disc and the housing of the chamber is due of the behavior of the liquid, a dynamic pressure on the cam mer limiting piston for the actuation of the friction clutch built up. There are only a few options here Characteristics of this coupling depending on the difference limit speed to vary; essentially only the filling degree and the viscosity of the viscous liquid can be freely selected. Another disadvantage is the low achievable Pressure level and the associated low power density.  

The invention further relates to the use of a clutch according to the invention in a differential gear for use in drive trains of motor vehicles, with a differential to be stored in a differential gear case inert, coaxial first and second driven bevel gears and at least two axially normal compensation bevel gears, with a friction clutch, the first friction elements te are rotatably held in the differential carrier and the second Friction elements non-rotatably to a first of the axle gears ten, and with a control device that one with visco comprises liquid-filled pressure chamber, its rotation housing of the differential carrier and a rotating one displaceable piston is formed. Extends in the same way the invention relates to the use of a clutch according to the invention in a differential gear of the type mentioned with a friction clutch, the first friction elements of which are non-rotatable the first of the axle shaft gears and their second friction elements are rotatably arranged to the second of the axle sprockets and otherwise a tax assigned to the axle sprockets device includes.

Differential gears of the type mentioned are known from US 4,012,968 known, the actuator being a positive displacement pump includes.

Other generic devices are those not previously published Couplings according to DE 43 27 519 A1, DE 43 43 307 A1 and DE 44 24 255 A1 known.

Arrangements of the type mentioned are in drive trains from Motor vehicles and agricultural machinery to produce one of the Speed difference dependent locking torque between two relative rotating parts used.

A preferred application relates to use in a force vehicle with a constantly and only occasionally driven Axle, with the clutch immediately in a driveline the latter axis is used. This will correspond appropriate drive train at a speed difference of the assigned neten axis compared to the continuously driven further axis  torque applied by the action of the clutch while the drive train when the speed is the same between the axes due to the effect of the clutch remains torque-free and the corresponding axis runs torque-free.

Depending on the conditions of detention on the constantly driven axle this results in a variation in the torque distribution between the two axes between 100%: 0 and 0: 100%, that is from 'total torque on the continuously driven axle' to 'total torque on the axle, which is only driven occasionally'. Accordingly, the part of the powertrain that is the last teren also leads to the maximum torque.

The operating states in which the constantly driven axis can not absorb any torque, that is, where the Spinning driven wheels freely are in the entire load column seldom rare. That means there will be rare start-up situations considered, in which usually the maximum torque is not is required. The necessary design for the maximum rotation moment therefore seems nonsensical.

Proceeding from this, it is an object of the present invention a differential speed sensing clutch with high performance te and selectable characteristics in a wide range in simple To provide construction that acts as a torque limiter.

The solution is a coupling, which is characterized is that rotating surfaces of the rotating body with counter surfaces a pump and control body located in the pressure chamber at least represent a closed shear channel through a bounded by walls laterally and between two ends circumferentially extending groove and a groove covering the groove is formed to this relatively rotatable surface that the Pump and control body in relation to the rotary housing between two end positions can be rotated to a limited extent, and that the groove through control openings arranged at their ends in the  Pump and control body with the one in the rotating housing Reservoir and with the pressure space between the piston and the Rotational body connected in the way that in the two End positions of the pump and control body each in the relative direction of rotation arranged at the front end of the groove Control opening communicates with the reservoir and the relati ver direction of rotation at the rear end of the groove Control port communicates with the pressure chamber, and that in addition another line for the first connection via the shear channel is provided for connecting the pressure chamber to the reservoir, in which a pressure relief valve opens from the pressure chamber to the reservoir is arranged to limit pressure in the pressure chamber.

With relative rotation between the rotatable parts of the clutch a pressure is built up in the pressure chamber, which is the friction plates axially applied to the friction clutch, so that these ten dieren to close the clutch. The pressure to build up is however through the pressure relief valve in the further line limits a maximum that a complete closure of the Friction clutch does not take place, but that according to that of Pressure in the pressure chamber creates axial force on the piston that acts on is limited according to the torque that is able to transmit the friction clutch in the same way is limited.

When installed in a powertrain to one only if necessary torque-loaded second drive axle of a vehicle is hereby over to this second axis portable torque limited to this maximum, so the This part of the drive train does not have the full engine torque ment must be interpreted. Notwithstanding this is the way in the event of slippage on the constantly driven axle, an all-wheel drive of the vehicle can be represented, in particular when starting greatly different coefficient of friction between the wheels of the enables both axes.  

Some other configurations serve to adapt to special Driving conditions as explained below.

In a preferred embodiment it is provided that the over pressure valve with the drive side of the clutch rotates and under the influence of centrifugal forces against the specified closing force is applied in the opening direction. This will make it easy understandably achieved that the clutch over portable torque for high vehicle speeds that a high rotational speed of the drive side of the clutch corresponds, can be limited or canceled. It it is known that an abrupt change at high speeds sel from two-wheel to four-wheel drive unstable driving conditions can cause. Such an abrupt connection of the only be if necessary driven axle can be done when the vehicle drives over an ice sheet. By the above means the clutch engagement is weakened. In the worst case it can also be provided that the pressure relief valve at an elevated Speed the further line under the influence of centrifugal forces also opens regardless of a form in the pressure room. In the In this case, the effect of the clutch is for high vehicle speeds abolished completely.

With a conventional constructive design of the overpressure vein tils with a ball resting on a valve seat a coil spring is pressed, the desired result Speed influence, especially when the ball is off-axis with run parallel to the axis of rotation or radial to the axis of rotation the valve bore or coil spring axis. During the print dependence of the pressure relief valve due to the spring design can be voted, it is possible regardless of the Centrifugal force characteristics through the ball mass and the ball order to vary relative to the axis of rotation. Instead of the ball any other valve body can be used accordingly.  

As an alternative to the direct inclusion of the speed flow on the function of the pressure relief valve is also possible Lich, another line in addition to the connection via the shear channel for connecting the pressure chamber to the reservoir to provide in which a centrifugal control valve is seen that rotates with the drive side of the clutch.

In a preferred development it is provided that temperature control lermittel are provided on the friction clutch, the over exceed a permissible maximum temperature control means on Activate the pressure relief valve in the opening direction or the temperature feeler means are provided on the friction clutch, which at A control valve exceeds a permissible maximum temperature til control in the direction of opening, that in yet another Lei device for connecting the pressure chamber to the reservoir is arranged for connection via the shear channel. It will assumed that operating conditions only arise for a short time, at which there is slip on the constantly driven axle and thus only on the clutch torque according to the invention only driven axle is transmitted if necessary. Because of the function of the pressure relief valve is constantly slipping given the friction clutch, so that an increase in temperature of the Friction clutch will be made. If the duration is excessive Operating state, for example when the vehicle is stuck this would lead to the destruction of the friction clutch.

With the above means it is achieved that the function the clutch at excessive temperature on the clutch plates is lifted until the natural cooling process Functionality resumes. The temperature sensor means can be integrated with the controls so that a temperature increase by acting on expansion elements un indirectly causes the mechanical switching of the control valve. In this area, however, an interpretation of the tax is preferred valve as an electrical switching valve, which is based on a tempera door sensor is controlled electrically.  

The function of the control device of the clutch is as Pressure drag flow is based on the principle of action based on relative to the shear of a viscous medium between two on the moving plates. With such a relative movement part of the medium, in each case related to one of the Plates, in the direction of movement of the other of the plates different. If a gap between two plates is essentially par allel to the relative direction of movement laterally as a scissor groove completed and delimited at two ends and with one in rich If the surface of the groove is covered, a Shear channel, depending on the size and direction of the rela Fluid movement from one end of the resulting shear channel to the other end. The discharge pressure is direct proportional to the length of the shear channel, the viscosity of the ge sheared the medium and the shear rate, i.e. the relative speed speed. With a suitable arrangement of this shear channel in such a way that this connects two chambers and the two the Parts forming the shear channel with one and the other of the rotating parts of a clutch are connected, a diffe generated delivery pressure, which is used can be that the pressure in a pressure chamber is increased, the acts on at least one piston, which the friction elements a friction clutch. In the described before direction is at least one shear channel by reversing for pressure generation regardless of the relative direction of rotation of the Parts used to each other. In a favorable way is before seen, at the time of reversing that before the pressure was removed used end of the shear channel directly with the reservoir connect so that the pressure reduction at this end does not have the entire shear channel length must be made.

In a further preferred embodiment, is rotated for illustration directional different characteristics of the An order provided in one of the two relative directions of rotation of the mutually rotatable parts only a partial length of the shear  channel to build up pressure by adding an additional Connection from the reservoir to the shear channel between its ends is provided, which is only free with a relative direction of rotation and is closed in the second relative direction of rotation.

In a similar preferred embodiment it can be provided that to display different characters depending on the direction of rotation characteristics of the arrangement in one of the two relative directions a direct connection between one between the ends of the shear channel and the section Pressure chamber is made to the effective channel length for the Shorten pressure build-up, which at the opposite relati ven direction of rotation is closed.

Basically, it is possible that the surfaces of the pump and Control body and the complementary counter surfaces of the rotation body, which form the at least one shear channel, normal to the axis or conical or cylindrical with respect to the axis of rotation are. The former shape with a disk shape is preferred Shape of the pump and control body and the rotating body.

A concrete embodiment is that the at least one Shear channel through a circumferentially extending groove in only one of the rotating surfaces of the pump and control body and relative by a complementary surface rotatable body is formed for this purpose.

It is important that spring means for the axial pressing of Rota tion body and pump and control body provided together so that the shear channel remains closed and the pressure between the rotating body and the piston.

After a first constructive execution, it is possible that two connecting channels between the reservoir and the pump and control body with the angular offset 2 α are provided to each other that a connection channel to the pressure chamber is arranged in the middle  and that the control openings in the control body make the angle offset α to each other, and that the control body around the Win kel α is rotatable and the groove extends over an angle (360 ° - α) extends.

In the aforementioned case, the reversal requires only a small one Angle of rotation α of the pump and control body.

According to an alternative to this, it can be provided that a Ver binding channel between the reservoir and the pump and control body it is provided that two connection channels to the Pressure chamber each with the angular offset 2 α to the former lie, and that the control body by the angle (360 ° - α) ver is rotatable and the groove extends over an angle of (360 ° - α) extends.

Here, locking takes place with relative reversal of the direction of rotation more gently with a time delay.

According to a further alternative, it is possible for a verb tion channel between the reservoir and the pump and control body seen that two connection channels to the Pressure chamber with the angular offset α to the former lie that the control body is rotatable by the angle α and that the groove overlaps the ends over a win kel of (360 ° + α) extends spirally. The function is that same as the first option mentioned.

It is also proposed that the control openings on the Form ends of the groove as axial bores in the form of a disk ten pump and control body are formed by one End face that seals at least in the area of the openings abuts an end wall of the chamber in the rotary housing, in of the connecting channels to the reservoir, to which in the ge groove lying opposite the second end face,  this second end face sealing with a radial The end face is in contact with only one of the end positions Control openings with a connecting channel in coverage.

It is also proposed for constructive execution that the Connection channel to the pressure chamber as a radial groove in a forehead wall of the rotary housing is formed in each of the two end positions with one of the two control openings on the Ends of the groove overlap.

Depends on the direction of rotation already mentioned different characteristics, it is possible that a wide right control opening as an axial hole in the disc-shaped Deten pump and control body is formed in the middle Area of the groove ends and only in one of the end positions an additional connection channel to the reservoir in coverage lies.

An embodiment in which provided is used for the same purpose is that a further control opening as an axial hole in the schei ben-shaped pump and control body is formed, which ends in the middle of the groove and only in one of the End positions with an additional radial connection channel overlaps with the pressure chamber, which acts as a radial groove in the rota tion housing is formed.

To limit the above-mentioned relative rotatability of the Pump and control body comes from the fact that a stop lug on the pump and control body in a limited in circumferential length Groove in the rotary housing engages as a rotary stop.

Depending on the desired course of the friction clutch locking torque above the differential speed, it is possible to correct effective forces. It is possible that Spring means are provided which are supported on the housing  and act on the fins on the side facing the piston hit, or that spring means are provided which are located on the Support the housing and the piston facing the lamellae act on the side or that spring means are provided, the preloaded between the piston and the friction clutch are arranged and they always act with a minimum force beat.

The reservoir can of the rotating housing and one with them around running axially displaceable spring-loaded piston or one spring-loaded membrane are formed or an elastic Compensating element in a chamber that forms the reservoir include. The viscous liquid contained in it can for example, be a dilatant medium, the viscosity of which Shear rate increases.

On the wording and content of the claims is total Referred.

For a better understanding of the new principle of action and Explanation of preferred constructive embodiments hereinafter referred to the drawings.

Show here

Figure 1 shows an outbreak of two relatively movable plates between which a groove creating a shear gap is formed in one of the plates.

Figure 2 shows a coupling according to the invention in longitudinal half-section.

Figure 3 shows a first embodiment of a pump and control disc with a rotating body in view (a) and in longitudinal section (b) as a detail in a first position.

FIG. 4 shows the pump and control disk and the rotating body according to FIG. 3 in a view in a second position;

Fig. 5, the pumping and control disc and the rotary body according to Fig 3 in view (a) and two longitudinal sections (b, c) in a third position.

Figure 6 shows a second embodiment of a pump and control disc with a rotating body in view in two positions (a, c) and in longitudinal section (b) as a detail.

NEN 7 shows a third embodiment of a pumping and control disc with a rotating body in two in view positio (a, c) and in longitudinal section (b) of a detail.

Figure 8 shows a fourth embodiment of a pump and control disk with a rotating body in view (a) and in longitudinal section (b) as a detail.

Figure 9 is a pumping and control disc as a detail in section (a) and front view (b).

Fig. 10 is a pump and control disk as a detail in rear view (a) and in section (b);

FIG. 11a, the pumping and control disc according 9b in view.

Fig. 11b is a pumping and control disc with a modified form of the shear channel-forming groove;

Fig. 12 a motor vehicle with a hitch be invention.

Fig. 1 shows the detail of a first plate or disc 1 and a second plate or disk 2, whose end surfaces 3, 4 abut one another. The first plate 1 is accepted as firm; the second plate 2 moves relative to this with the speed V _R Ge. In the end face 3 of the first plate 1 , a groove 5 with a rectangular cross section and laterally delimiting walls 6 , 7 is formed. Groove 5 and end face 3 form a shear channel 8 which receives a viscous medium. The element of the shear channel under consideration has the length l _sp and the height or depth s. When moving the plate 2 , the medium behaves in the shear channel according to the specified linear speed profile, which refers to the fixed plate 1 . On the upper surfaces, of course, conditions of detention apply to both plate 1 and plate 2 . In relation to plate 2 , the speed profile would therefore look reciprocal. Based on the plate 1 , a pressure p and a mass flow Q result in the shear channel due to the shear.

Since the applications shown here are not based on relative linear movements, but rather on relative rotational movements, the groove forming the shear channel is preferably formed circumferentially as shown in one of FIGS. 2 to 12.

FIG. 2 shows a clutch arrangement 11 which comprises a controllable friction clutch 12 in the form of a multi-plate clutch and a speed-sensing control arrangement 13 . The Rei tion clutch comprises a housing 14 in which outer plates 15 are held in a rotationally fixed manner, and a hub 16 on which inner plates 17 are arranged in a rotationally fixed manner. The friction clutch can be acted upon by means of a piston 19 . This is part of the control arrangement 13 mentioned , which is arranged in the housing 14 and comprises the axially displaceable piston 19 and a rotary housing 20 which rotate with the housing 14 . Both form a pressure chamber 21 in which a disk-shaped rotating body 22 and a disk-shaped pump and control body 23 lie. The rotary body 22 is rotatably connected to the aforementioned hub 16 , which is driven. The pump and control body 23 can be rotated to a limited extent with respect to the rotary housing 20 by a rotary stop (not shown) which engages in a peripheral groove (not shown) in the rotary housing 20 . An in the piston 19 O-ring serves as spring means 35 and thus the tight contact of the rotating body 22 on the pump and control body 23rd

When changing the direction of rotation of the hub 16 via toothing medium-driven rotary body 22 , this takes the pump and control body 23 from its end position determined by a rotary stop and circumferential groove into the other end position determined by a rotary and circumferential groove. A reservoir 26 is furthermore formed in the rotary housing 20 and is limited by an axially displaceable annular piston 27 . This is supported on the housing 20 via plate springs 28 , so that the reservoir 26 always compensates for changes in volume in the pressure chamber 21 . In the Rota tion housing 20 , an axial connecting channel 30 can be seen , which is in the circumferential position shown with a control opening 31 in the pump and control body 23 in overlap. The control opening 31 is located at one end of a shear channel 38 , which is formed by a circumferential groove in the pump and control body 23 and the surface of the rotary body 22 . The parts rotating relative to each other are each sealed by seals against one another. The gap between the rotating body 22 and the piston 19 radially outside the O-ring 35 is to be regarded as part of the pressure chamber 21 . The screw 39 in a housing bore 40 is used to fill or vent the pressure chamber and the reservoir. Disc springs 25 are supported on the housing 14 and act on the piston 19 with a counterforce to the effect of the pressure in the pressure chamber.

In addition to the connection between the reservoir 26 and the pressure chamber 21 , which is produced through the housing bore 30 and the control opening 31 , the shear channel 38 and a further control opening, which cannot be seen in the section shown, a further line 91 is provided for the connection, in which a pressure relief valve 92 is inserted. The pressure relief valve is formed by two intersecting bores 93 , 94 , which are each closed by screw plugs 95 , 96 , and by a valve ball 97 , which rests on a valve seat 98 and is acted upon by a compression spring 99 . The function of the Steueranord voltage is such that at existing relative speed between the driving hub 16 and the possibly entrained housing 14 in the pressure chamber 21 as a result of the action of the shear channel 38 pressure is built up, which acts on the piston 19 to actuate the friction clutch 12 . Due to the function of the Überdruckven valve 91 , the pressure in the pressure chamber and thus the force of the piston is limited to a permissible maximum pressure so that the friction clutch transmits only a permissible maximum torque with continuous slippage.

In Fig. 3, a rotary housing 20 and a pump and control body 23 are shown as a detail in view and in axial section. The circumferential groove 37 can be seen in view, which is delimited by lateral walls 54 , 55 and at the ends of which there are control openings 31 and 33 . The control opening 33 also shown in section is located above the connec tion channel 32 in the rotary housing. The control opening 31 located at the other end overlaps with a radial connecting channel 43 ( not shown in section) in the rotating body. The position of a further through opening 30 in the rotary housing 20 is shown with dashed lines. In section and in view is shown with dashed lines indicates the rotary stop 41 located on the back of the pump and control body 23 and the circumferential groove 42 , which limit the rotation of the pump and control body 23 relative to the rotary housing 20 .

In Fig. 4, the same details as in Fig. 3 are shown only in view and designated by the same reference numerals.

The rotary stop 41 is, however, in a middle position in the circumferential groove 42 between the two possible end positions. As a result, both the control opening 31 at one end of the groove 37 , at which the pressure has previously been built up, is still connected to the connecting channel 43 to the pressure chamber, and also the second control opening 33 , which was previously connected to the reservoir via the connecting channel 32 , which has not yet lost the overlap with the connecting channel 32 . In this way, a pressure relief from the connecting channel 43 and thus from the pressure chamber to the connecting channel 33 and thus to the reservoir can take place.

In Fig. 5 the same details as in Figs. 3 and 4 are shown in view and two sections and are designated by the same reference numerals. The rotary stop 41 , however, assumes the opposite end position in the circumferentially limited groove 42 . Now the control opening 31 with the second connec tion opening 30 to the reservoir in coverage, while the second control opening 33 is in communication with the connecting channel 43 to the pressure chamber. The pressure build-up now takes place at the end of the groove 37 at the control opening 33 . The position of the first connecting channel 32 relative to the reservoir is shown in dashed lines in the view and now has no function.

In Fig. 6, a rotating body 22 and a pump and control body 23 is shown in axial section and in axial view in two different positions in a ver compared to FIGS. 3 to 5 modified version. As far as the details agree, they are provided with the same reference numbers. To this extent, reference is made to the preceding description.

In addition to this, the pump and control body 23 has an additional control opening 44 in the groove 37 which lies between the two control openings 31 and 33 . Furthermore, the Rota tion housing 20 has an additional connection channel 45, the illustrated in in Fig. 6 with Fig. 5a matching position of the rotation stopper 41 in the circumferential limited groove 42 and thus of the pump and the control body 23 relative to the Rota tion housing 20 with the control port 44 is in cover. In this way, an effective pressure build-up does not take place over the entire length of the shear channel, but rather only over the Winkelbe region between the control opening 44 and the control opening 33 , a lower pressure being present at the connecting channel 43 . In the opposite direction of rotation of the Rota tion body compared to the rotary housing with the position of pump and control body 23 and Rota tion housing 20 shown in Fig. 6c, the control opening 44 and the connecting channel 45 are offset from each other, so that a pressure build-up over the entire length of the shear channel the control opening 33 to the control opening 31 and thus leads to a higher pressure.

In Fig. 7, a rotary body 22 and a pump and control body 23 in axial section and in axial view in two different positions in a ver compared to FIGS. 3 to 5 modified version is shown. As far as the details agree, they are provided with the same reference numbers. To this extent, reference is made to the previous description. In addition, the pump and control body 23 has an additional control opening 46 and the rotary housing has an additional connecting channel 47 . In the position of the rotary stop 41 in the circumferentially limited groove 42 and thus of the pump and control body 23 relative to the rotary housing 20 shown in FIG. 7a and corresponding to FIG. 5a, the control opening 46 and the connecting channel 47 are in register. In this way a pressure increase in the shear channel is performed only over a range from the standing Winkelbe via the communication passage 30 with the reservoir in connection control port 31 to the control port 46 and the connecting channel 47, which opens into the pressure chamber. The remaining angular range from the control opening 46 to the control opening 33 , which is in overlap with the connecting channel 43 , is not effective. The pressure build-up in this relative direction of rotation between the rotating body and the rotating housing is therefore less than in the opposite direction of rotation, which is shown in FIG. 7c and corresponds to a position of the control openings to the connecting channel 43 according to FIG. 3a. Here, the control opening 46 and the connecting channel 47 are offset from one another and are not effective, so that the pressure builds up over the entire length of the shear channel from the control opening 33 to the control opening 31 .

In FIGS. 8a and 8b are a rotary housing 20, a pumping and control body 23 and a piston 27 substantially in conformity with FIGS. 5a and 5b. Corresponding details are given the same reference numbers. In this regard, reference is made to the description of FIGS. 3 to 5.

In addition, a throttle bore 49 is provided in the rotary housing, which communicates with the reservoir 26 . On the abut the surface of the pump and control body, a recess 50 is provided, which is designed so that in one of the end positions of the rotary stop 41 opposite the circumferential groove 42, a connection between the pressure chamber and the reservoir is effective, while in the second relative circumferential position the throttle opening 49 is covered by the rear of the pump and control body 23 , so that it becomes ineffective. In this way, the pressure in the pressure chamber is reduced in one relative direction of rotation of the parts. In the other relative direction of rotation of the parts against each other, however, so that here too a different pressure build-up occurs depending on the direction of rotation.

The cuts are each contrary to the standard-compliant representation the views shown.

In FIGS. 9a and 9b is a pumping and control element 23 of the type already described several times before as a detail be inscribed, wherein the control openings 31, 33 and the groove 37 and the rotation stopper identifiable as details.

In FIGS. 10a and 10b is the pumping and control element 23 of Fig. 9 from the rear side and in section. Here, a surface area 51 can be seen , in which the control openings 31 , 33 lie and which is designed such that it can lie sealingly on the connecting channels 30 , 32 , 43 , 47 depending on the position. The surface area 51 is limited in the circumferential direction so that it can alternately open or close the throttle bore 49 previously explained with reference to FIG. 8. The rest of the surface has a plurality of ring ribs 53 on the back to reduce friction and adhesion to the housing. A surface 52 lying opposite the surface 51 carries the rotary stop 41, which also protrudes further in height.

The cuts are each in a standardized representation of the Views shown.

FIG. 11a shows another pump and control body 23 in the illustration according to FIG. 9b for comparison. The groove 37 has a circumferential length of 360 ° - α, so that when rotated by the angle α, a control opening 31 assumes the position previously assumed by the control opening 32 .

In Fig. 11b, a groove 37 b is shown, which has the circumferential length of 360 ° + α, the groove being slightly spiral. Here too, when the pump and control body 23 b is rotated by the angle α, the control opening 31 b assumes the angular position previously maintained by the control opening 33 b or vice versa.

A motor vehicle 201 is shown in schematic top view in FIG. 12, which reveals the following details. The motor vehicle has two front wheels 202 , which are driven by the drive parts of a front axle 203 with an axle differential 204 , and two rear wheels 205 , which are driven by the drive parts of a rear axle 206 with an axle differential 207 . It has an internal combustion engine 208 installed at the front as a drive source, which is coupled to a multi-stage or continuously variable transmission gear 209 for adapting the speed range of the internal combustion engine to the speed range of the motor vehicle.

The output of the reduction gear 209 is connected to the input of the axle differential 204 of the front axle 203 as well as via a through drive at the same speed to a clutch unit 210 according to the invention, which drives the input of the differential 207 of the rear axle 206 via a longitudinal shaft 211 . The torque introduced is distributed to the wheels of the respective axle shaft via the axle differentials 204 , 207 . The clutch 210 according to the invention is installed so that one of the mutually rotatable parts with the drive parts of the transmission gear 209 and the other of the mutually rotatable parts is connected to the connecting parts of the longitudinal shaft 211 .

Claims (24)

1. Coupling for the transmission of torques between two parts ( 14 , 20 ; 16 , 24 ) which can be rotated relative to one another, which comprises a friction clutch ( 12 ), the friction elements ( 15 , 17 ) of which are connected to one and the other of the mutually rotatable parts 14, 20; 16, 24) are rotatably connected, wherein the friction clutch (12) via a ver slidable piston (19) being at least acted upon, the filled a viscous fluid, bounded on one side with a reservoir (26) pressure chamber (21) connected , whose rotation housing ( 20 ) is formed by one of the rotatable parts ( 14 , 20 ) and the piston ( 19 ) rotating therewith and in which a rotating body ( 22 ) connected to the other of the rotatable parts ( 16 , 24 ) rotates, characterized by
that surfaces of revolution of the rotating body (22) with counter-surfaces of the pressure chamber (21) lying pumping and STEU erkörpers (23) representing at least a closed shearing channel (38) laterally limited by a walls and extending between two ends in the circumferential direction groove ( 37 ) and a surface ( 36 ) covering the groove and being relatively rotatable is formed,
that the pump and control body ( 23 ) relative to the Rota tion housing ( 22 ) between two end positions is rotatable ver
that the groove ( 37 ) through control openings ( 31 , 33 ) arranged at its ends in the pump and control body ( 23 ) with the reservoir ( 26 ) located in the rotary housing ( 20 ) and with the pressure chamber ( 21 ) between the piston ( 19 ) and the rotary body ( 22 ) is connected in such a way that in the two end positions of the pump and control body ( 23 ) the control opening arranged in the relative direction of rotation at the front end of the groove ( 37 ) communicates with the reservoir ( 26 ) and the control opening arranged in the relative direction of rotation at the rear end of the groove ( 37 ) communicates with the pressure chamber ( 21 ), and
that in addition to the first connection via the shear channel ( 38 ) a further line ( 91 ) for connecting the pressure chamber ( 21 ) to the reservoir ( 26 ) is provided, in which a pressure chamber ( 21 ) to the reservoir ( 26 ) opens over pressure valve ( 92 ) to limit the pressure in the pressure chamber is net. 2. Coupling according to claim 1, characterized in that an additional control opening ( 44 ) in the pump and control body ( 23 ) is provided to represent a direction of rotation asymmetrical characteristic, via which a central portion of the shear channel ( 38 ) in only one of the two End positions communicated with the reservoir ( 26 ). 3. Coupling according to claim 1, characterized in that an additional control opening ( 46 ) in the pump and control body ( 23 ) is provided for representing a direction of rotation asymmetrical characteristic, via which a central portion of the shear channel ( 38 ) in only one of the two End positions communicated with the pressure chamber ( 21 ). 4. Coupling according to one of claims 1 to 3, characterized in that spring means ( 35 ) for axially pressing the rotary body ( 22 ) and pump and control body ( 23 ) are provided together. 5. Coupling according to one of claims 1 to 4, characterized in that the at least one shear channel ( 38 ) through a groove ( 37 ) in only one of the rotating surfaces of the pump and Steuererkör pers ( 23 ) and by a complementary adjacent surface ( 36 ) is formed on the rotating body ( 22 ) which can be rotated relative thereto. 6. Coupling according to one of claims 1 to 5, characterized in that the surfaces of the control body ( 23 ) and the complementary complementary surfaces of the rotary body ( 22 ), which form the at least one shear channel ( 38 ), axially normal or conical or circular-cylindrical in relation to the axis of rotation. 7. Coupling according to one of claims 1 to 6, characterized in that
that for the first connection of two connecting ducts (32, 34) between the reservoir (26) and shearing channel (38) α with the angular offset 2 are provided to each other, and that centrally between a connecting channel (43) from the shear channel (38) to the pressure space (21 ) is arranged, and
that the control openings ( 31 , 33 ) in the pump and control body ( 23 ) have the angular offset α to one another, and
that the control body ( 23 ) can be rotated by the angle α and the groove ( 37 ) extends over an angle 360 ° - α. 8. Coupling according to one of claims 1 to 6, characterized in that
that a connection channel between the reservoir ( 26 ) and the shear channel ( 38 ) is provided for the first connection,
that in the circumferential direction two connec tion channels from the shear channel ( 38 ) to the pressure chamber ( 21 ) each with the angular offset 2 α to the former, and
that the control body ( 23 ) can be rotated by the angle (360 ° - α) and the groove ( 37 ) extends over an angle of (360 ° - α). 9. Coupling according to one of claims 1 to 6, characterized in
that a connection channel between the reservoir ( 26 ) and the shear channel ( 38 ) is provided for the first connection,
that in the circumferential direction two connec tion channels from the shear channel ( 38 ) to the pressure chamber ( 21 ) each with the angular offset α to the former,
that the control body ( 23 ') can be rotated by the angle α and that the groove ( 37 ') extends over an angle of (360 ° + α) in a spiral shape while overlapping the ends. 10. Coupling according to one of claims 1 to 7, characterized in that the control openings ( 31 , 33 ) at the ends of the groove ( 37 ) as axial bores in the disc-shaped pump and control body ( 23 ) are formed, which of the one End face, which at least in the area of the openings ( 31 , 33 ) lies sealingly against an end wall in the rotary housing ( 20 ), in which connecting channels ( 32 , 34 ) lead to the reservoir, to which the groove ( 37 ) lying in the opposite second end face , This second end face sealing with an end face of the Rotationskör pers ( 22 ) in contact, in each end position only one of the control openings ( 31 , 33 ) with a connecting channel ( 32 , 34 ) is in overlap. 11. Coupling according to one of claims 1 to 10, characterized in that the connecting channel ( 43 ) of the first connection to the pressure chamber ( 21 ) is designed as a radial groove in an end wall of the Rota tion housing ( 20 ), which in each of the two end positions one of the two control openings ( 31 , 33 ) at the ends of the groove ( 37 ) is in register. 12. Coupling according to claim 2, characterized in that the further control opening ( 44 ) of the first connection is designed as an axial bore in the disk-shaped pump and control body ( 23 ), which ends in the central region of the groove ( 37 ) and only in one the end positions with an additional connecting channel ( 45 ) to the reservoir ( 24 ) overlap. 13. Coupling according to claim 3, characterized in that the further control opening ( 46 ) of the first connection is designed as an axial bore in the disc-shaped pump and control body ( 23 ), which ends in the central region of the groove ( 37 ) and only in one the Endpositio NEN with an additional radial connecting channel ( 47 ) to the pressure chamber ( 21 ) is in overlap, which is formed as a radial groove in an end wall of the rotary housing ( 20 ). 14. Coupling according to one of claims 1 to 13, characterized in that a rotary stop ( 41 ) on the pump and control body ( 23 ) engages in a circumferentially limited groove ( 42 ) in the rotary housing ( 20 ). 15. Coupling according to one of claims 1 to 14, characterized in that spring means ( 25 ) are provided which are supported on the Ge housing ( 14 ) and act on the piston ( 19 ) with a counterforce to the pressure in the pressure chamber ( 21 ) . 16. Coupling according to one of claims 1 to 14, characterized in that spring means ( 85 ) are provided which are supported on the Ge housing ( 14 ) and support the piston ( 19 ) with an additional force to the pressure in the pressure chamber ( 21 ) . 17. Coupling according to one of claims 1 to 16, characterized in that spring means are provided, which are arranged biased between the piston ( 19 ) and the friction clutch ( 12 ) and always apply a minimum force. 18. Coupling according to one of claims 1 to 17, characterized in that the reservoir ( 26 ) from the rotary housing ( 20 ) and a circumferential axially displaceable with this in the direction of the minimum volume spring-loaded piston ( 27 ) is formed. 19. Coupling according to one of claims 1 to 18, characterized in that the pressure relief valve ( 92 ) rotates with the drive side of the clutch and is acted upon by centrifugal forces on the valve body against the action of the valve spring ( 99 ) in the opening direction. 20. Coupling according to claim 19, characterized in that the pressure relief valve ( 92 ) at a predetermined increased speed, the further line ( 91 ) opens independently of a form in the pressure chamber ( 21 ) by the centrifugal forces on the valve body. 21. Coupling according to one of claims 1 to 18, characterized in that in addition to the connection via the shear channel, another line for connecting the pressure chamber ( 21 ) to the reservoir ( 26 ) is provided, in which a centrifugal control valve is arranged, that rotates with the drive side of the clutch and opens by centrifugal forces on the valve body at a predetermined speed. 22. Coupling according to one of claims 1 to 21, characterized in that temperature sensor means are provided on the friction clutch ( 12 ) which control the control means on the pressure relief valve ( 12 ) in the opening direction when a permissible maximum temperature is exceeded. 23. Coupling according to one of claims 1 to 21, characterized in that in addition to the connection via the shear channel, another line for connecting the pressure chamber ( 21 ) to the reservoir ( 26 ) is provided, and that temperature sensors are provided on the friction clutch medium which control a control valve, which is arranged in the line, in the opening sense when a permissible maximum temperature is exceeded. 24. Coupling according to one of claims 1 to 23, characterized, that they are in a motor vehicle with one constantly and one occasionally driven axis as dependent on differential speed Effective clutch in the drivetrain to be driven occasionally axis is used.